Porous materials find use in a wide variety of applications in the chemical, biomedical, electronic and optoelectronic arts. Desirable features of porous materials include pore size, regularity of pore distribution and ease of fabrication. Of particular interest are porous layers having regularly arrayed nanometer scale pores. Such layers, sometimes called nanostructured layers, can be fabricated in a number of ways. For example pores larger than about 50 nm can be made, e.g., using nanoparticle templation. Smaller pores can be made in a variety of ways.
For example, commonly assigned co-pending U.S. patent applications Ser. Nos. 10/290,119, 10/303,665 and 10/319,406 describe nanostructured porous layers made using a technique known as surfactant templation. Nanostructured porous layers made using surfactant templation can potentially have regularly arrayed nanometer-scale pores. Current surfactant templation techniques have typically produced nanostructured porous layers with pores 2 nm −10 nm or larger than about 50 nm, which is often a major disadvantage.
Many applications can potentially benefit from the use of 10-50 nm pores. For example, charge-splitting networks can be made by filling the pores in a nanostructured porous layer made, e.g., of Titania (TiO2), with organic materials such as dyes, pigments and conjugated polymers. Unfortunately, some of these pore-filling materials are relatively large molecules that may not completely fill pores smaller than about 20 nm in diameter. Pores larger than about 50 nm in diameter tend to make the charge-splitting network less efficient. Applications other than optoelectronics can also benefit from 10-50 nm pores. Unfortunately, there is no known technique for making a porous layer with regularly arrayed pores in 10 nm to 50 nm size range.
Thus, there is a need in the art for an improved nanostructured layer with pores between about 10 nm and about 50 nm in diameter and a corresponding method of making such a nanostructured layer.